Zaccaria MPU board progress...

[Homepin]

We started the artwork for the reproduction Zac MPU quite a while back now and were side tracked by a couple of other smaller projects.

Anyway we are now back onto this project and here is a snapshot of our progress around the EEPROM area. As previous posts show, we are replacing the obsolete CA3081's with 7 transistors each. This is a little messier than using the ICs but this board uses 7 of these chips and we feel common garden variety transistors are cheap and easy to get so our new board will 'do the distance' better than if we used the original chips.

This is a long complicated job so we will be at it longer than originally anticipated.

A HUGE thankyou to forum member Skybeaux whose assistance with this project has made it possible.

[Retropin]

Oh cool stuff... thats a horrible little cct between the Eproms when i rebuilt mine it was very frustrating.
Looking forward to these

[MartyJ]

Some very good news for the Zac owners out there.  Seems to be growing more and more in Australia too!

A Mike & Skybeaux project !  Awesome stuff and no doubt will be an A1 product.

[ktm450]

Nice work again Mike 

[Pinfan]

Awesome work guys !

One day i WILL be adding a Zac to my collection and quite possibly this board.

[Skybeaux]

Some very good news for the Zac owners out there.  Seems to be growing more and more in Australia too!

A Mike & Skybeaux project !  Awesome stuff and no doubt will be an A1 product.

No credit for me Marty , i'm no part of it , i only lent him the processor chip.
Mikes the one with all the brains 

Happy to help out your doing a great job Mike

[Strangeways]

The only reason I avoid Zaccaria games is because of the electronics. I've seen MANY parted out because of this. I'm VERY happy that this board will save many machines from the same fate. Many collectors in the USA will be very pleased to hear about this !

[The pinballist formally known as Dean Morgan]

What processor are you using in replace of the Signetics 2650A?

[Homepin]

We have progressed a little on this project. This area shows the top right of the PCB and our replacement transistors for the top two CA3081 IC's

and Dean, this board uses the same parts as trhe original including the processor. We are on the track of a hidden stash of them BUT in most cases people building this board will have a processor from their corroded PCB that will likely be OK.

[The pinballist formally known as Dean Morgan]

Awesome, let us know if you get any 2650As' as i will take a couple as spares, down to my last one.

Good luck with the board, i will also take one so let us know when complete

[Homepin]

Choofing along with this project, here is a small update around the micro:

[pulstar]

This looks great... a lot of work involved in what you are doing here!
Are you doing it from the Circuit diagrams or from a bare original PCB?

I'm interested in spare 2650a 's as well ... that's the worst thing about buying a non working zac... hoping your processor is not toast.

The only other issue I have is displays... but i'm going to do a set of boards using some off the shelf led's to fix this issue.

Great Effort... I know how long it took me to do the displays which are simple compared to this.

[Homepin]

This looks great... a lot of work involved in what you are doing here!
Are you doing it from the Circuit diagrams or from a bare original PCB?

I'm interested in spare 2650a 's as well ... that's the worst thing about buying a non working zac... hoping your processor is not toast.

The only other issue I have is displays... but i'm going to do a set of boards using some off the shelf led's to fix this issue.

Great Effort... I know how long it took me to do the displays which are simple compared to this.

We have replacement display boards in the works as well. We are having custom made LEDs made to the exact specifications (sizes etc) as the originals in both sizes. This is a little way off at this stage however as the order qty for custom displays is HUGE!!!

[Homepin]

We are probably about halfway through this board re-design. Still a fair bit to do and then a HUGE amount of double checking....

[Homepin]

We're getting there.......